powell



W. T. POWELL. SEW-AUTOMATIC TELEPHONE SYSIEM.

APPLICATION FILED JUNE 26, I5. I

Patented Sept. 9, 1919.

3 SHEETSSHEET l fnusrzfm" W. T. POWELL.

SEMI-AUTOMAIIG TELEPHONE SYSTEM.

"memos HLED sun: 26. IBIG.

1,315,443. PatentedSept. 9,1919.

' 3 SHEET55HEET 2. "5i d1 Hffur' may W. T. POWELL.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATION mes um 20. me.

1,31 5,443. PatentedSept. 9, 1919.

I I I I I H [aver-12271" UNITED STATES PATENT OFFICE.

WINFRED T. POWELL, OF CHICAGO, ILLINOIS, ASSIGNOB TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

1,3 l 5,-hl3.

Specification of Letters Patent.

Patented Sept. 9, 1919.

To all where it may concern:

Be it known that I, Wnvrnno T. POWELL, a citizen of the United States of America, and a resident of Chicago, Cook county, Illinois. have invented certain new and useful Improvements in Semi-Automatic Telephone Systems, of which the following is a specification.

My invention relates to telephone systems in general but more particularly to automatic or semi-automatic telephone systems.

An object of my invention is provision of improved means for intermittently applying ringing current to a called subseribefis line to operate the substation signals together with means whereby the calling line receives a buzz, or tone in the receiver at the same time ringing currentis thus applied.

A furtl'ler object of my invention is the provision of a connector switch which is released by the subscriber that last hangs up his receiver. lVhen used in a connection extending to a manual switchboard my improved connector is provided with means for reversing the current to operate a disconnect signal at the switchboard when the calling subscriber hangs up his receiver to release the connection. The connector however, is not released until the operator at said board withdraws the plug of the cord circuit from the connection extending toward the connector.

A further object of my invention is the provision of a connector switch that reverses the flow of current to the calling line for the purpose of operating a call register and that also reverses the flow of current in the direction of the called line to operate a signal. It is to be understood that other suitable devices may be operated by these reversals of current and my invention is not.

to be restricted to the particular devices shown.

A still further object of my invention is to provide a very efficient and highly improved connector switch embodying these and other features hereinafter mentioned in the specification.

As herein illustrated my invention relates particularly to semi-automatic telephone systems but it will readily be understood that certain features of this invention are directly applicable to purely automatic telephone systems.

To the foregoing and other useful ends tending to increase the ellicieiwy and general serviceability of telephone systems in general, my invention consists of matters here inafter set forth and included in the appended claims.

The features of this invention will be more readily understood by reference to the accompanying drawings, in which* Figure 1 represents a diagrammatic layout of a telephone systeni wherein the group of stations at A are taken to he automatic substations having line switches C in the eX- change X. The line switches have access to selectors E which have access over the second level of their bank contacts to connector switches H. The switches H through their second level of bank contacts may extend a connection to a called automatic substation such as are in the group A or over the first level df their bank contacts the said switches H may extend a connection over one of the trunk lines Z to the private branch exchange Y. The trunk lines Z terminate in line switches D at the main exchange X and in answering jacks J on the switchboard of the private branch exchange Y. Cord circuits F having plugs P and R, are under control of an operator to complete a connection from the trunk jacks J to a multiple jack M of a called substation in the group B. The cord circuits may also be used to complete a local connection between any two substations at the exchange Y. If a substation of the group B desires a connection with any of the automatic substations of the group A, the operator, through the medium of a calling device associated with her cord circuits controls selectors F. similar to selectors E, and connectors H to find the particular substation. The substations B are provided with the usual answering jacks N and multiple jacks M. The cord circuits are provided with supervisory signals so that the operator is informed when a disconnect is desired.

Figs. 2, 3 and 4 taken together represent a complete connection between a calling automatic substation A and a called manual substation B in a telephone system, embodyin the principles of this invention.

The substation A (Fig. 2) comprises the usual receiver 4, transmitter 5, ringer 6, and condenser 7. It is also provided with a suitable impulse sending mechanisn'l for controlling the automatic switches. which mechanism is represented by a pair of impulse springs S and an in: mlsc Wheel 5), which latter may he controlled by a finger-hold dial (not shown) in such a. way that the impulse springs may he momentarily separated a number of times cm'respoiuliug to the rc= spective digits of a called number. This impulsesending mechanism may he similar to that shown in United States Letters latcut to .l. (l. Blessing, No. l,llll, .)l, granted December 1, 1914.

The subscrihefls individual or line switch U (lfig. 2) is of the general type of sub-- scribers switcl'i shown in British patent to T. (i. Martin, No. t lt!) of 1910, being hoiw ever, of the particular type disclosed in United States Letters Patent to i New forth, J12, No. 13,901, reissued April 1 1915. Associated with the suhstation A at the central ollice is the call register M haw ing the operating magnet 133.

The master switch H is of the same general type as that shown in British patent to it. TY. James, No. 20,301 of 19 W, being, how ever, of the particular type disclosed in British Patent No. 11-19 ynieviously referred to. The function of lhe master switch, as is well known, is to maintain the plunger-s of all idle individual switches, with which it associated, in position to engage the tcrmi nals of an idle trunk line.

The selector switch E (Fig. 2) is of the same type of selector switch disclosed in British patent to Automatic Telephone Manufacturing Co, Ltd, No. 25-1-3 of 1914. Among other details the selector switch comprises a hank of contacts arranged in horizontal rows or levels, which contacts are adapted to be engaged by a set of wipers 10, 11 and 12 carried upon a. shaft (not shown) which has a primary and secondary move ment controlled by the vertical and rotary magnets 13 and 14. The said magnets he ing controlled through the medium of the line relay 15. Release relay 1G and relay 17 are slow-acting i. 0., slow to release their respective armatures when their energizing circuits are broken. Relays 18 and 19 are controlling and switching relays respectively. The release magnet is indicated at 20, which performs the function of restoring the selector to its normal position. The oil'- nornial springs 21 and 22 are closed when the switch shaft makes one or more steps from its normal position and are separated when the shaft returns to normal position.

The connector switch H (Fig. 3) is of the general type of connector switch shown in United States Letters Patents No. 815,176 granted March 13, 1906, to Keith, Erickson & Erickson, the circuits being modified to adapt the switch for operation in a system in which the switching mechanism is controlled hy impulses transn'iitted over two sides of a line in series, as shown in the aforesaid British Patent No. 2513 of 1911. Auunu other details the connector comprises a ban: of contacts arranged in horizontal rows or levels, which contacts are adapted to he engaged by a set oi wipers Lil, til, 25, and 26 carried upon a shaft (not shown) which has a primary and secondary movement con trolled. by the vertical and rotary magnets 27 and 28. The, various operations of the switch are controlled through the medium oi the line relay 29. The hack-bridge relay St) is provided through which current is sup plied to a called line. The release relay 3i and private control relay 32 are slow acting, Z. (2., slow to release their armaturcs when their energizing circuits are broken. The magnet 33 is the usual release magnet while 2H is the husy relay and 335 is a ring cut-oil ielay. The private magnet I'll} controls the side switch wipers UT and 38 ill the well known manner. The wiper cut-on relay 3!! closes the wiper circuits after llie sideswilch reaches third position. llelay it) is used to reverse the relation ol lmck-lrridgc relay windings with respect to the called line. Off-normal springs 41 and is make contact when the switch shaft is one or more steps from its normal position. VVheu the switch shaft is released. the springs 41 and 12 are separated.

The line or trunk switch I) is in all rcspccts similar to the switch 0.

The jack equipment comprises the locking relay #3, sleeve relay it, condenser 45 and signal 16. The cord circuit F comprises the sleeve relays 47 and -18, elcctro-polariZed re lay 49 of a well known type in which the current flowing through the lower .vii'iding is always in one direction and the current in the upper winding may flow in either direclion to assist or oppose the. flux produced by current in the lower winding, impedance 50, relays 51 and 52 through which battery for talking purposes is supplied to substation l3, supervisory signals 53 and 54, key K to coir nect the calling device 55 with the cord circuit and the key K for connecting the operators talking equipment to the cord circuit. The key K is for connecting ringing can rent from a suitable source for signaling purposes.

The substation B is of a well known type, and is provided at the central olli 'e with the line and cut-off relays 56 and 57.

The batteries l and 1% supply current for operating and talking purposes at the exchanges X and Y respectively. The busy machine comprising the induction coil 177 and interrupter 178, supplies a busy tone which is used to inform calling lines Whenever an attempt is made to complete a connection with a line that is in use.

The exchange at Y may be provided with a plurality of trunk lines Z extending from the exchange X. The trunk lines may all he listed under one number, the number corresponding to the first trunk line. With this arrangement the automatic. switching mechanism will be operated to extend the coiniection to the first trunk. If the first trunk is busy the connector switch autoimttically rotates to the second trunk. It the second trunk is also busy it will proceed to the third trunk, etc. If however, the last trunk is also busy the connector will not rotate any further, but will stop and give the calling subscriber a busy tone.

In order to give a clearer understanding of my inventiolnit will now be explained how a connection can be established between the line of a calling automatic substation A and :1 called substation B of a private branch exchange. Since the apparatus herein disclosed is in general well known in the art and described in the publications herein re ferred to, its operation will be explained in a more or less general manner. The sub-- scriber at station A upon removing his receiver proparatoiy to making a call, closes an energizing circuit for line relay 58 of the switch C. This circuit extends from ground G through springs 59, line conductors and substation A, springs (30 and the relay 58 to the battery B. The line relay upon energizing closes a circuit for pull-in winding ()1 which operates to thrust the plunger {not shown) on the end of a plunger arm (32 into a bank of contacts, thereby forcing sp'ringr-s (33, 61-, 65 and 66 into engagement with springs 67, 68, 69, and 70, respectively, thereby extending the connection to the selector switch E. These springs form the terminals of a trunk line leading to a selector switch E. A plurality of such sets of springs are provided which extend to a plurality of selector SWit-ClleS. The energizing circuit for wind- .ing 61 extends from ground (it through springs 71, Winding 61, contacts 72 to the battery B. The cut-ofi' arm 73 is also op erated to remove the line relay 58 from control of the calling substation. The relay 58, being slow acting, maintains the circuit of pul1-in winding 61 for a short time, after its own circuit is broken, to insure that the line switch will be held in its operated position until a holding ground is supplied from the selector E to the holding or cut-off winding H. It should be stated that the pull-in winding is strong enough to operate both the plunger arm 62 and the cut-01f arm 73 while the cut-off winding H is only strong enough to operate the cut-off arm 73 but will hold the plunger arm 62 in its operated position after it has been thrust in by the pull-in winding, \Vhen the connection is thus extend l to the selector R an energizing circuit is closed for the line relay 15 which upon energizing closes a ircuit from round (1 through springs 75 and 76 and therelease relay 16 to the battery B. The

release relay upon energizing supplies a holding ground from (it through springs 77, along conductor 78, springs (38 and (34-, to a )Oillll where the circuit divides, one path extending through the holding winding 74: to the battery 13 while the other path extends along conductor 80 to the calling line pri vate bank contact; 81, and multiples thereof. Ground potential on the private bank contacts protects the substation A against seizure. A branch ol. this (Jil'rllll extends through the right hand winding of the magnet 63 and contacts (51 to the battery 13. The left hand winding of magnet (33 is at this time included in the circuit of line relay 15 and carries current in the direction to oppose the right hand Winding. It should be stated that both windings of magnet (33 must assist each other before its ai'nuitnre can be attracted. l'lowever, the right hand winding alone will retain the a rmatnre operated after the same has once been at tracted.

Assuming the eXchallge in which the line of substation l terminates to be number 221. The calling subscriber now operates his calling device for the first digit 2; thereby causing the impulse springs 8 to be momentarily separated twice, each time breaking the circuit of the line relay 15 ot the selector E. The slow acting relay 16 does not deenergize during the momentary interruptions of its circuit by relay 15 and therefore each time that relay 15 deenee gizes a circuit, is closed from ground i through springs 75 and 82, springs 83, springs 84 and 85, relay 17 and the vertical magnet 13 to the battery I). The vertical magnet receives two impulses over this circuit and operates to raise the shaft Wipers tWo steps to a position opposite the second row or level of bank contacts, at the same time closing springs 21 and 22. The slow relay 17 is energized by the first impulse of current transmitted through it and main tains its armature in the attracted position during the remaining impulses of the digit. In its energized position said relay closes a circuit from ground Gr through springs 86 and 87 and the relay 18 to the battery B. The relay 18 upon energizing forms a locking circuit for itself from G through springs 7 7, conductor 7 S, springs 88, springs 22, springs 89 and 90, and the said relay 18 to the battery B. When the relay 17 deenergizes after the last impulse is delivered to the vertical magnet, the relay 18 remains energized, and the circuit of the rotary magnet 14 is closed from G as traced to spring 90 thence through springs 87 and 91, springs 92, and the rotary magnet to the battery B. The rotary magnet, upon energizing rotates the shaft wipers one step and opens its own circuit and that of relay 18 by separating springs 92 and 58.

the first trunk line is idle the relay 18 dergizes as soon as the spring contact 88 is opened. If this trunk line, however, is busy the private wiper 11 linds ground on the private contact with which it engages, which is transmitted to relay 18 through springs 8%) and 90 and thereby prevents it from deiincrgizin". The rotary magnet, however, deenergizes when springs 92 are opened regardless of whether the rel-a3 17 remains energized or not. I f the relay 17 remains energized the circuit of rotary magnet ll will again be closed as soon as its armature drops back far enough to close sprin s 92 and 88. The rotary magnet will, thereiore, operate in a manner to advance the wipers step-by-step over the contacts until the non-grounded contact of an idle line is reached by the wiper 11, whereupon relay 18 deiincrgizes. The relay 18, upon deilncrgizing, whether after one or more operations, permanently breaks the circuit ol' the rotary magnet, and closes the circuit of the switching relay 10, which circuit extends from ground G as previously traced to spring 80 thence through spring 023 and the switching relay 19 to the battery B. The relay 19, upon energizing disconnects the line relay 15 and extends the connection over the heavy conductors shown through the wipers 10 and 12 to the connector switch H.

The line relay 29 of the switch H thereupon becomes energized and completes a circuit for release relay 31 which in turn, upon energizing, completes a circuit from ground Gr through springs 9-CL and 95, release conductor 96, private wiper 11, point 97, where the circuit divides, one path eX- tending through springs 89 and 93 and the relay 19 to the battery B. Another path extends through springs 22, springs 88, springs 68 and 64, throu h the holding winding 74 to battery B. nother path extends along conductor 80 to private contact 81 and multiples thereof. These circuits maintain the selector E and line switch G in their operated position after the original energizing circuit is broken by the relay 16, which denergizes shortly after the line relay 15 is disconnected from the line. The ground potential along conductor 96 extends to the private bank contacts in the banks of other selectors which have access to the said connector H, to guard against further seizure.

When the calling device at substation A is operated for the second digit 2, the circuit of the line relay 29 is momentarily opened twice. Since the relay 31 is slow acting, it does not denergize during the momentary interruptions of its circuit by relay 29, so that each time the latter relay deenergizes a circuit is closed extending from ground G through springs Q8 and 99, springs 100,

slow relay 32, vertical magnet 27. side switch wiper 37 (in lirst position) to the battery B. The vertical magnet receives two impulses over this circuit and operates to raise the shaft wipers 23, 24-, 25 and 20 two steps to a position opposite the second row or level of bank contacts. The slow relay 32 energizes when the first impulse is transmitted and remains energized during the subsequent impulses ol the digit. In its energized position the said. relay 32 closes a circuit from ground. ti through springs 102 and 101 and the lower wind-- ing of the private magnet 30 to the battery B. After the last impulse delivered the relay 32 deenergizes and opens the circuit of the private magnet which deenergizes and permits the side switch wipers 37 and 38 to pass to second position. The morement of side switch wiper $17 from lirst to second hosition transtcrs the battery connection from the vertical magnet 27 in tin rotary magnet 2S. The substation calling device is now operated for the last digit 1, in response to which the comu-ctor line relay 29 operates to transmit one impulse through the relay 32 in series with the rotary magnet 28. This circuit extends from G through relay 32 as before traced, thence through springs 103, rotary magnet 28, side switch wiper 37 (in second position) to the battery B. The rotary magnet operates to rotate the shaft wipers into engagement with the first set of contacts oi the second level. If the first contact, which is the terminus of the first trunk line, is busy there will be a ground potentia. on private bank contact 104. When the private wiper 26 encounters this busy contact a circuit will be closed from the ground potential on said contact 104, through private wiper 26, side switch wiper 38 (in second position) and the upper winding of the private magnet 36 to the battery B. The side switch wipers 37 and 38 will thus be held in second position when. slow relay 32 de'cinergizes, after the last impulse has been transmitted through it to the rotary magnet, and opens its circuit 'for the lower winding of the private magnet. A circuit is then closed from ground G through springs 102 and 105, springs 106. springs 107, springs 103, rotary magnet 28, side switch wiper 37 (in second position) to the battery B. The rotary magnet operates in response to this impulse to advance the shaft wipers to the second set of bank contacts, and to close the contact of springs 108 whereby a circuit is closed for the lower winding of private magnet 36. A circuit is also closed for interrupter relay 110. These circuits extend from ground G through springs 108 to a point 109, where one path extends through the lower winding of the private magnet 36 to the battery B, while the other path extends through interrupter relay 110 to the battery'B. The private magnet is thus held energized, and the interrupter relay operates to separate springs 106 thereby opening the rotary magnet circuit. The rotary magnet thereupon releases its armature which breaks the contact of springs 108. If the second set of bank contacts is busy the rotary magnet will be energized in the above manner to advance the shaft wipers to the third set, etc. The private contacts of the last trunk line, as for instance contacts 111 and 112 are permanently connected together by the conductor 113, so that a potential 011 contact 111 will be supplied to both private Wipers 25 and 26 should they be rotated onto the said contacts. It now it is assumed that all the trunk lines leading to the private branch exchange are busy, when the private Wipers engage the contacts 111 and 112 circuits Will be extended from the ground potential thereon over both Wipers 25 and 20. Since the springs 114 of relay 32 are adjusted to make contact before spring 102 engages spring 105, the ground over private Wiper 25 will be extended through springs 115 and 110, springs 11-1, busy relay 3% and the side switch 37 (in second position) to the bat-- tery B. The relay 3%, upon energizing, forms a locking circuit for itself from. ground G through springs 4-1, springs 117 and 116 over the circuit above traced. By separating springs 103 the rotary magnet circuit is opened so that further rotation is impossible, and by the closure of springs 118 a busy tone from the busy machine I is supplied to the calling line. By the closure of springs 117, 116 and 119 a circuit is closed to hold the private magnet 36 energized and maintain the side switch in second position. This circuit extends from ground G through springs -11, springs 117, 116 and 119 and the lower Winding of private magnet 36 to the battery B. The busy tone is supplied from the machine I through springs 118 over heavy conductors to and through the substation A back over heavy conductors through the upper Winding of line relay 29 and back to the busy machine.

It is thus seen that this connector operates step-by-step to select an idle trunk line and it all trunk lines of a certain division are busy, when the switch reaches the last trunk line it will lock thereon, prevent further rotation and supply a busy signal to the subscriber originating the call.

The calling subscriber restores his receiver when he recognizes that his connection cannot now be completed. The line relay 29 of connector H is thereupon dei ncrgized and opens the circuit of release relay 31 which dei nergizes to remove the holding ground G from release conductor and to close a circuit from G through springs 94 and 120,

springs 42, springs 121 and 122 and the release magnet 33 to the battery B. The release magnet, upon energizing, operates to restore the switch-shaft and wipers to normal position. When the shaft reaches normal, the springs 41 and 42 are separated thereby opening the release magnet circuit and unlocking all relays which were held locked from ground G The removal of ground from release conductor 96 causes switching relay 1%) and holding winding 71 to dei uergize. When the relay 19 deenergizes a circuit is closed from ground G through springs 75 and 82, springs 83, springs 8+1 and 123, springs 21, and the release magnet 20 to the battery B. The release magnet restores the switch shaft and Wipers to normal whereupon springs 21 and 2:1 are separated. \Vhen the circuit of holdingwinding 71 is opened, the plunger arm 62 retracts and withdraws the plunger from the bank contacts, u'hile cut-oii' armature 73 again bridges the line relay 58 across the line. in readiness for another call.

Suppose now that the first trunk line is idle. The private wiper 20 upon engaging contact 101 and finding it free of ground, will not prevent the passage of: the side switch wipers to third position after the slow relay 32 deiinergizes responsive to the impulses transmitted through said relay is the rotary magnet. \Vhen side switch u'ipcr 38 reaches its third position contact. point. a circuit is closed from ground G through said wiper 38. private Wiper 26, bank contact 101, cut-off or holding winding 121 of the line switch I) to the battery B. The cut-off armature 125 is operated to remore relay 126 from the trunk line. A circuit is also closed from said ground (i and \vipcr 38 through. the relay 3%), side switch wiper 37 (in third position) to the battery B. The relay 39, upon energizing, prepares a circuit through the Wipers 23 and 24 over which ringing current may be projertcd to the trunk line conductors 127 and 128 from the generator G. The group ringing relay 129 is energized intermittently through the medium of the interrupter 130 and t 10 battery B which may be the same battery shown at B. When the relay 129 is energized generator current will flow from one terminal "of the generator G through contacts 131 and 132 over conductor 133, springs 134 and 135, springs 131, springs 137 and 138, trunk conductor 127, condenser 45, contacts 139 and 140, upper winding of relay 43, trunk conductor 128, wiper 24, springs 139 and 140, springs 141, springs 142 and 143, upper winding of relay 355-, battery B and ground to ground G to the other terminal of the generator G. When the relay 129 is dei nergized the generator circuit is broken when armature 132 disen'gages contact 131. The armature 132 upon restoring engages its back contact 180, thereby ubstituting ground G for the generator lead which leads to (1" through the generator (1. If a circuit ndependent of the condenser be estal'ilished when armature 132 is upon its front contact 131 or upon its back contact 180, the relay 35 will inm'iediately be energized as hereinafter explained. The calling; .-uibstation receives a signal every time ringing current is projected to ring a called line, due to the inductive relation of the windings of said relay 35. This circuit for the calling subscribcrs station extends from the battery lead through lower winding of relay 35, conductor 154, lefthand Winding of relay 30, condenser 161, over the heavy conductors to and through the substation A, back over heavy conductors, condenser 163 and the right hand windingof relay 30 to the battery lead. This current through relay 36 is not strong enough to operatirely energize the same. The relay It? is so constructed and adjusted that it will not energize in the above circuit. The relay 4 energizes and forms a locking circuit for itself extending from ground ti through rontacts 141 and 145, springs 146 and 147 to the battery B. The signal lamp 46 which is included in a circuit from G through contacts 144 and 14S and the lamp 46 to battery B, begins to glow to notify the operator that a connection is desired. By the closure of contacts 149 and 150. the condenser 45 is short circuited, thus causing relay 35 of the connector to opcratircly energize to disconnect the. ringing circuit, prepare the talking circuit and form a lookingcircuit for itself extending from ground U through springs 41, springs 151 and 152 and the lower winding of relay 35 to the battery B. hen the operator notices the lamp 46 ilpwing she answers the call by inserting t e plug P- into the pick J, thereby con'ipleting a circuit from ground G throu% h cut-oil relay 44, sleeve conductor of plug and jack J, and the sleeve relay 47 to the battery B. The relay 44, upon energizing, breaks the contacts of springs 139 and 140 and 146 and 147. The relay 47, u on energizing, closes contacts 151 and 152. C iintact 15-2 prepares a, circuit for supervisory lamp 53, which is now 0 on at springs 153 of electro-polarized re ay 49-. (ontacts 151 close a circuit from ground G through said contacts 151 and the lower Winding of relay 49 to the battery B. The upper winding of relay 49 at this time carries current, which is opposed to that current flowing the lower Winding, as follows: from ground G through springs 41, springs 151 and 152, conductor 154, left hand Wind'- ing or' back bridge relay 3-0, conductor 155, springs 156 and 142, sprin s 141, springs 140 and 139, wiper 24, con uctor 128, riiicg of jack J, and plug P, springs of key upper winding of relay 49, impedance 50, contacts of he K, tip of plug P and jack J, conductor 12 wiper 22$, springs 1256 and 137, springs 136, springs 135 and 157, eonductor 158, and the right hand winding of the back bridge relay 30 to the battery B. The back-bridge relay, upon energizing, reverses the low of current from the windings oi the line relay 29 to the calling line. The reversal of current in the left hand whaling of meter magnet 63 (Fig. causes the two windings to assist one another and the armaure is attracted to operate the meter to register the call. The left hand winding is short-circuited by the springs 65 as soon as the armature is operated. The right-hand winding;- being of sullicicnt strength to hold the armature until the eonnertion is released. A further result of the energization of relay 30 is the opening of spring 159 and the closure of springs 121 and 160 whereby the circuit of lamp 164 is held open and a circuit is prepared for relay 40. and the release magnet circuit held open at another point. The operator presses the key or bulton K to connect her telephone apparatus l) across the cord F to talk to the calling subscriber. Upon finding; out that the substation B is desired, the operator inserts plug 1 into the multiple jack M and presses the key or button K to project ringing current to signal the station B. \Vhen the plug inserted a circuit is closed from ground G through relay 48, sleeve of plug ll and jack M and cut-Oil relay 5'? to the battery B. Relay 57 energizes to disconnect the line relay 56 while relay 4S energizes to close the circuit of lamp 54 at contact 165. When the subscriber at B takes off his receiver. current for talking purposes is suplicd through re lays 51 and 52. Relay 51 energizes to open the lamp circuit at contacts 166 to notify the operator that the called station. has answered. The two stations may now hold conversation. After the conversation is COH'I- pleted the subscriber B upon restoring his receiver dcenergizes relay 51 which causes the disconnect signal lamp 54 to glow. When the callingsubscriber A restores his receiver the line relay and release relay 29 and 31 are de'einergized and the selector E and line switch C are restored to normal in the manner hereinbefore described. The connector switch is not released for the reason that the circuit of the release magnet 33 is open. The back bridge relay being energized, a circuit is closed as follows when relay 31 decnergizesz from ground G through springs 94 and 120, springs 42, springs 121 and 160, conductor 167 and the relay 40 to the battery B. The relay 40, upon energizing, reverses the direction of current flow through the upper Winding of eleetro-polarized relay 49. Both windings of relay 49 now carry current in the direction to assist each other and close the contacts 153 whereby the signal lamp 53 glows over a circuit from ground G through. springs 153, springs 152 and lamp 53 to the batter 15. A further result of the cnergization of relay 10 is the closure of a circuit from ground (11 through springs 168 and the lower winding of private magnet 36 to the battery 1). The private magnet upon energizing closes a circuit from ground G through springs 169 over the release conductor ac to the private bank contacts of all selector switches which have access to the connector H, to prevent seizure of the connector switch as long as this condition exists. The relay,1l0 is also energized at this time but is without any particular utility. The operator, upon noticing signal lamps 53 and 5+ glowing, knows that a disconnect is required and acoirdingly she pulls the plugs J and ll from the jacks J and M. 11011 plug It is withdrawn from jack M, the circuit of rela =15 and 57 broken, whereby the circuit of lamp 54; is opened at springs 165 and the line relay 5G is bridged across the line of station 13. When plug 1 is withdrawn from jack J, the circuit of relays all and 4-7 and back-bridge relay 30 is broken. Relay ll, upon deiincrgizing restores to normal the circuits originally closed. Relay 47, upon deencrgizing, opens the circuit of lamp signal 53 at springs 152 and at springs 151 opens the circuit through lower winding of reh l9. The baclobridge relay 30, upon d ergizmg. opens the circuit of rover-nag rcla -10 and closes a circuit from ground (2 through springs 9-1 and 120, springs 42, springs 121 and 1:32, and the release magnet 33 to the battery B. The reversing relay 40, upon dcinergixing, restores its springs to normal position thereby opening the circuit oi 1)1l\{l10 magnet 36 and relay 110. The release magnet upon energizing restores the connector aha it and wipers to normal position, its own circuit being opened when the shaft reaches its lowest position. When the connector removes ground from the holding winding 124 of switch D, the cut-off armature 125 falls back to bridge the relay 126 across the trunk conductors 127 and 128. If, however, the operator pulls the plug P from the jack J before the calling station A has hung up his receiver, the back-bridge relay, upon deiinergizing will not release the connector switch but a circuit will be closed from ground G through springs 41, springs 151, 152 and 168, springs 159 and the signal lamp 164 to the battery B. This signal indicates to an attendant in the exchange X that a called line has disconnected from a calling line while the calling line has the receiver off its switch hook.

If the subscriber at substation B desires the medium of the line relay 56 and lamp signal 169. The operator inserts plug 1t into answering jack N, closing a circuit for relays 48 and 57 as pointed out. ltclays 51 and 52 being energized over the line and substation circuit of station ll. The operator after ascertaining from the subscriber at ll the number of the desired automatic substation, inserts the plug 1 into jack .l and throws the key K to connect her calling device 55 to the plug 1. A circuit is closed which may be traced from ground (P at line switch I) through springs 170, trunk conductor 12S, ring of jack J and plug 1, contacts of key K, impulse springs of call" ing device 55, contacts of key K. tip of plug 1 and jack 5'. return conductor I'JT. springs 171, and the relay 126 of line switch I) to the battery 13. The relay 1213. upon micrgiz-aing. operates the switch I) to seize an idle trunk line leading to a selector switch similar to the selector it, in the same manner a wa explained with regard to the switch The switch 1) is controlled by a mastcr switch (not shown) which is similar to the master switch S. The conductors 17!. 173 and 11.3 are assumed to lend to a selector switch adapted to be seized by the switch 1). The conductor 171i, of course leads to the master switch bank in the same manner as indicated with respect to spring (39. Through the medium of the calling device the operator controls the selector to find a connector similar to switch H, which connector finally connects with the normal contacts 81. 1Y 176. and 17'? ot' the desired line. The elcctro polarized relay 45) has current flowing through its windings in direction to assist each other as soon as the key K is restored to normal. The circuit of signal lamp 53 is therefore. closed and the lamp glows. 'hen the called subscriber removes his receiver the baclobridge relay of the connector reverses the direction of current flow in the upper \i'inding of relay 4.. The current flowing in the two windings of relay 49 Will now be in opposition and the contacts 153 will be broken whereby the lamp 53 is extinguished to inform the operator that the called subscriber has answered the call. After the conversation is completed the subscribers upon restoring their receivers cause the glowing of supervisory signals 53 and 54 in the manner hercinbe'l' ore described. The operation of withdrawing the plugs causes the release of the automatic switching 1ncchanism. If, however, substation A is busy there will be a ground potential on private contacts 81 and 179 Which will prevent a connection from being completed to the busy line at the same time holding the connector locked and giving the operator a busy si nal as was explained with regard to a cal ing subscriber.

When a subscriber at the substation A Sin desires to obtain a connection with another mihserilnat an automatic substation in the group A, he operates the connector II to lind the bank contacts of the desired line which will be taken as 170", 177", 17%) and Hi. which are shown in Fig. 3. The con' tarts beingthe same as those shown associated with the -substation A (Fig. 2). The called substation being' provided with equipment at the central ollice and substation which in the same in all respects as that shown For the substation A. The connection is extended to the called automatic substation in substantially the same manner as previously described. When the subscriber tllitdd'lr the call register M of the calling line is operated. If the calling subscriber hangs up his receiver heloro the called anb .--criher dot so, battery current will he. re versed to the called line but the call rcgiuter oi maid called line cannot la operated llt cauw n illu'l' winding carries current when the line is called.

it is thus seen that I provide a \cry ellicicni tetephone fiYSi OlII in which ringing current is cut oli' the instant a metallic path is established, as for instance, by the shortcireniting of a conden er or the substituting of talking equipment at a substation for the ri ging: circuit including a condenser. I also provide means whereby ringing: current is induced to the calling line so that the calling subscriber gets a. buzz in his receiver each time that ringing current is being projcctcd to signal :1 called line. My improved connector switch is constructed so that it will be released by the last party who rcstores his receiver. or if the connection extcnds to an operator the said switch will he released by the operator if she pulls out the plug after the calling party has hung up. In this manner I prevent the useless tripping of individual switches. I further provide means in the connector for controlling a signal before an ope ator whereby the operator is informed When a calling or called. party answers a call or desires to be disconnected.

While I have illustrated and described the features of my invention in connection With a telephone system embodying automatic switches of a particular type, it is to be understood that other types of switches may be modified to embrace these features. Certain details of these improvements may have wider application and I do not limit myself to the exact arrangement and construction shown and described.

What I claim as my invention is:

1. In a telephone system, a first line, a second line, means for initiating a call over the first line and for extending a connection from the said first line to said second line, said means includinga link circuit, conducimam tors for said link, a signal for the first line, means in said link for controlling said signal, a source of current connected to said controlling means without causing the same to operate said signal, means for disconnecting said lines, and means responsive to the disconnect operation. for then reversing the connection of said source to uaid controlling: means for operating said signal.

2. In a telephone system, a first line, a second line, means for initiating a call over the first line and for extending a connection from the said first line to said second line, said means including a link circuit, conductors for said. link. a signal for the first line, means in said link for controlling said sig nal, a source of current connected to said controlling means. without causing the same to operate said signal, and meanshontrolled by the first line For reversing the rr-mnection of said source to said controlling means i'or operating said signal.

3. In a telephone system, a group ol first lines. a group of second lines. a link circuit con'nnon to said first lines for extending a connection to any of said second lines, means for initiating a call over one of said first lines and for extending a comiection from said first line to one of said second lines. said means including said link circuit, a

uignal for the calling line. controlling means for said signal in said link circuit, a Source of current connected to said controlling means without causing the same to operate said signal, means for disconnecting said lines, and means responsive to the disconnect operation for then reversing the coin nection of said source to said controlling means to operate said signal.

el. In a telephone system, a group of first lines, a group of second lines, a. link circuit common to said first lines for extending a connection to any of said second lines, means for initiating a call over one of said first lines and for extending a connection from said first line to one of said second lines, said means including said link circuit, a signal for the calling line, controlling means for said signal in said link circuit, a source of current connected to said controlling means Without causing the same to operate said signal, and means controlled by said first line for reversing the connection of said source to said controlling means to operate said signal.

5. In a telephone system, calling and called lines, means including a link circuit and progressively movable switch mechanism for establishing a connection between said lines, a signal for said calling line in said link circuit, a source of current, means for supplying current to said link from said switch mechanism without operating said signal, means for disconnecting said lines,

and means responsive to the disconnect operation for then reversing the current supply to operate said signal.

6. In a telephone system, calling and called lines, means including a link circuit and progressively movable switch mechanism for establishing a connection between said lines, a signal for the calling line, a source of current, means in said link for controlling said signal, means for supplying current to said controlling means from said switch Without operating said signal and means controlled by the calling line to re vegse the current supply to operate said signa 7. In a telephone system, calling and called lines, means including a link circuit and progressively movable switch mechanism for establishing a connection between said lines, a signal for said calling line in said link circuit, a source of current, means for supplying current to said link from said switch mechanism without operating said signal, and means controlled by the calling subscriber for reversing the current supply to operate said signal.

8. In a telephone system, calling and called lines, means including a link circuit for establishing connection between two of said lines, a signal for the calling line, means in said link for controlling said signal, a source of current, means for supplying current from said source to said con trolling means without operating said signal, and means controlled by the calling line for reversing the direction of current flow to operate said signal.

9. In a telephone system, a calling and called line. means including a two-conductor link circuit for establishing a connection between said lines, a signal for the calling line, means in said link for controlling said signal, a source of current, means for supplying current in one direction from said source to said controlling means without op erating said signal and means controlled by the calling line for reversing the direction of current flow to operate said signal.

10. In a telephone system, calling and called lines, means including a progressively movable switch for establishing a connection between a calling and a called line, a source of current for operating purposes, a signal for the calling line, means in said switch for supplying current in one direction toward said called line without operating said signal, and means for reversing the direction of current flow to operate said signal.

11. In a telephone system, calling and called lines, means including a progressively movable switch for establishing a connection between a calling and a called line, a source of current for operating purposes, a signal for the calling line, means in said switch for supplying current in the direction of said called line without operating said signal and means controlled by the calling line for reversing the direction of current flow to operate said signal.

12. In a telephone system, calling and called lines, means including a progressively movable switch for establishing a connection between two of said lines, a source of current for operating purposes, a signal for the calling line, means for controlling said signal, means in said switch for supplying current from said source in one direction to said controlling means Without operating said signal, a relay for reversing the direction of current flow to said controlling means to operate said signal, a second relay for controlling the first relay, and means under control of the calling line for controlling said second relay.

13. In a telephone system, a connector switch, calling and called lines, means under control of a calling one of said lines for seiZ- ing said switch, means for operating said switch to extend the connection from said calling line to one of said called lines, release mechanism for said switch, means for disconnecting from said connection, means whereby said release mechanism is operated by the last one of said lines that disconnects from said connection, a source of current for operating purposes, a signal for the calling line, means for controlling said signal, means for supplying current to said controlling means in one direction while said connection is established without operating said signal, and means for reversing the current flow to said controlling means to op erate said signal. when the calling line disconnects said first means from the connection.

14. In a telephone system, a connector switch, calling and called lines, progressively movable switch mechanism under control of a calling line to extend a connection to said connector switch, means for operating said connector switch to extend the connection to one of said called lines, release mechanism for said connector switch, means for disconnecting said progressively movable switch mechanism from said connector switch without operating said connector release mechanism, a source of operating current, a signal for the callin line, means for controlling said signa-, means for supplying current from said source to said controlling means without operating said signal while said calling and called lines are connected, means for reversing the current supply to said controlling means to operate said signal when said progressively movable switch mechanism is disconnected from said connector switch.

15. In a telephone system, a connector switch, a calling line and a plurality of other lines, progressively movable switch mechanism under control of the calling line to extend a connection to said connector switch, means for operating said connector switch to extend the connection to one of said other lines, release mechanism for said connector switch, means for disconnectingsaid progressively movable switch mechanism from said connector switch without operating said connector release mechanism, a source of operating current, a signal for the callin line, means for controlling said signal, means for supplying current from said. source to said controlling means with out operating said signal while said lines are connected, means for reversing the current supply to said controlling means to operate said signal when said progressively movable switch meclmnism is disconnecttal from said connector switch, and means under the control oi said last mentioned other line for oi'ierating said connector release mechanism to release said switch.

16. In a telephone system, a connector switch. a calling line and a. plurality oi other lines, progressively movable. switch mechanism under control of a calling line to extend a connection to said connector switch, means for operating said connector switch to extend the connection to one of said other lines, release mechanism for said connector switch, means for disconnecting said progressively movable switch mechanism from said connector switch without operating said connector release mechanism a source of operating current, a signal for the calling line, means for controlling said signal, means for supplying current from said source to said controlling means without operating said signal while said calling and called lilies are connected, means for reversing the current supply to said controlling means to operate said signal when said pro ressively movable switch mechanism is isconnected from said connectorswitch, means under control of said last mentioned other line for operating said connector release mechanism to release said switch, and means for guarding said switch from seizure until the said last mentioned other line operates said release mechanism. 17. In a telephone system, a connector switch, a calling substation, a line for said substation terminating at the exchange, progressively movable switch mechanism for said calling substation for extending a conneetion to said connector switch, a manual switchboard, a trunk line extending to said man'ual board, means for operating said switch to extend said connection over said trunk line to said manual board, a link cireuit at said manual board, a signal in said link for said calling line, release mechanism for said progressively movable switch mechanism and for said connector switch, means controlled by the calling substation for operating the release mechanism of said progressively movable switch mechanism to release the same Without operating the release mechanism of said connector switch, and means operable in said switch for then reversing the current supply to said controlling means to operate said signal to indicate that the progressively movable switch mechanism has been released.

18. In a telephone system, a connector switch, a calling substation, a line for said substation terminating at the exchange, progIGSS'lVOlY movable switch mechanism for said calling substation for extending a connection to said connector switch, a manual switchboard, a trunk line extending to said manual board, means for operating said switch to extend said connection over said trunk line to said manual board, a link cii cuit at said manual board, a signal in said link for said calling line, release mechanism for said progressively movable switch mechanism and for said connector switch. means controlled by the calling substation for operating the release mechanism oi said progressively movable switch mechanism to release the same without operating the release mechanism of said connector switch, means operable in said switch for then reversing the current supply to said controlling means to operate said signal to indicate that the progressively movable switch mechanism has been released, and means comprising said link circuit for controlling the release mechanism of said cormector switch to release the same.

In a telephone system, a calling substation, a lin 'For said substation terminating at the exchange, a connector switch, progressively movable switch mechanism for said calling substation for extending a connection to said connector switch, a trunk line extending to a manual switchboard, means for operating said switch to connect with said trunk line whereby said connection is extended to said manual board, a called substation terminating in said manual board, a link circuit for completing the connection between said substations, a source of operating current, a. signal for the calling substation at said board, means for controlling said signal, means in said switch for supplying current from said source to said controlling means without operating said signal, release mechanism for said progressively movable switch mechanism, release mechanism for said connector switch, means controlled by the calling substation for operating the release mechanism of said progressively movable switch mechanism to release the same, means operable when said progressively movable switch mechanism is released for reversing the current supply to said controlling means to operate said signal and means comprising said link circuit for controlling the release mechanism of said connector switch to restore the same.

20. In a telephone system, a calling substation line, a called substation line, progressively movable automatic switches and a cord circuit for connecting said lines, a sig nal for said calling line, means in said cord circuit for controlling said signal, a source of current, means in one of said switches for supplying current to said controlling means in the direction to render the signal inoperative, means controlled by the calling line for releasing certain of said switches, means operable in said one switch to reverse the current supply to said controlling means, to operate said signal when said certain switches are released, to indicate that the calling substation. line is disconnected from the connection.

21. In a telephone system, a main ex change, a branch exchange, trunk lines extending between said exchanges, a calling substation line terminating at the main ex change, a connector switch for connecting with said trunk lines, progressively movable automatic switches controlled by the calling line to extend a connection over said connector switch and one of said trunk lines to said branch exchange, an operators board at the branch exchange, a called substation line terminating in said operators board, a cord circuit at said board for connecting said lines, a source of current, a signal for the calling line in said cord circuit, means for controlling said signal, means in said connector switch for supplying current to said controlling means in the direction to render said signal inoperative, release means for said progressively movable automatic switches, release means for said connector switch, means controlled by the calling substation for operating the release means of said progressively movable automatic witches to release the same, means operable when said progressively movable automatic witches are released for reversing the direction of current supply to said controlling means to operate said signal, and means including a circuit for controlling the release means of said connector switch to release the same.

22. In a telephone system, calling and called substation lines each terminating at the exchange or central office, signals for said lines at their respective substations, means for connecting a calling line with a called line, a source of current for operating said signals, a circuit for said source of current, a relay having two windings, means for including one of said windings in a connection comprising the circuit of said source and the signal of said called line to operate said signal, means including the other winding of said relay for producing a signal at the calling substation when the said source and signal of said called line are thus connected, a back-bridge relay and means in cluding the first winding of said first relay for disconnecting said source of current as soon as a metallic connection is established across said second line and for extending said second line to said back-bridge relay.

23. In a telephone system, a first line, a second line, signals for said lines, a source of current for operating said signals, a relay comprising a pair of windings, means for including said source in a circuit with one of said windings and the signal of said second line, means including the other winding of said relay for giving said first line a signal when the said source and signal of said second line are thus connected, and a locking circuit for said relay, said circuit including said other winding. said first winding excluded from the locking circuit.

24. In a telephone system, a subscribers line, a trunk line, an automatic switch for extending a connection from said subscribers line to said trunk line, means for releasing said connection, and for operating a disconnect signal over said trunk line, and means for preventing the release of said switch when the connection is released.

25. In a telephone system, a subscribers line, a trunk line, an automatic switch for extending a connection from said subscribers line to said trunk line, means for releasing said connection, and for operating a disconnect signal over said trunk line, means for preventing the release of said switch when the connection is released, and means controlled over the trunk line for releasing said switch.

26. In a telephone system, a subscribers line, an operators position, an automatic switch for extending a connection from the line to the operators position, a disconnect signal for said line at said operators position, and means controlled by said subscriber for operating said signal without releasing said switch.

27. In a telephone system, a subscribers line, an operators position, an automatic connector switch for extending a connection from the line to the operators position, a disconnect signal for said line at said operators position, and means controlled by said subscriber for operating said signal without releasing said connector switch.

28. In a telephone system, an automatic connector switch, means for operating said connector switch to pick out the individual line of the called subscriber directively in accordance with the last digit of the called number, and means associated with said connector switch to enable it also to automatically select an idle one of several lines; and automatic means controlled by a called subscriber for releasing the connector switch.

29. In an automatic telephone system, a connector switch, provided with means for directively locating and establishing connection with a called subscribers line, and

provided also with means for automatically selecting an idle one of several lines; and 10 means also controlled by the called subscriber for releasing the said switch.

Signed by me at Chicago, 111., this 22nd day of June, 1916.

WINFRED T. POWELL.

Copies 0! this patent may be obtained for five cents each, by addressing the "Gommissioner of Patents, Washington, D. G." 

